15,580 research outputs found

    Specifying mobile network using a wp-like formal approach

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    The paper aims at providing a formal system, motivated by Dijkstra’s weakest precondition logic, for specifying mobile network. The paper shows how mobility can be specified using a state and transition based approach, which allows mobile hosts to be treated as nodes in a traditional statically structured distributed system. Another goal is to reason formally about the possible behaviors of a system consisting of mobile components. The handover procedure serves as an illustration for the notation. The contribution of the paper is the development of a style of modeling and reasoning about the temporal properties that allows for a straightforward and thorough analysis of mobile systems.Keywords: weakest precondition, mobile computing, specification, verification, safety, handover

    Proceedings of International Workshop "Global Computing: Programming Environments, Languages, Security and Analysis of Systems"

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    According to the IST/ FET proactive initiative on GLOBAL COMPUTING, the goal is to obtain techniques (models, frameworks, methods, algorithms) for constructing systems that are flexible, dependable, secure, robust and efficient. The dominant concerns are not those of representing and manipulating data efficiently but rather those of handling the co-ordination and interaction, security, reliability, robustness, failure modes, and control of risk of the entities in the system and the overall design, description and performance of the system itself. Completely different paradigms of computer science may have to be developed to tackle these issues effectively. The research should concentrate on systems having the following characteristics: • The systems are composed of autonomous computational entities where activity is not centrally controlled, either because global control is impossible or impractical, or because the entities are created or controlled by different owners. • The computational entities are mobile, due to the movement of the physical platforms or by movement of the entity from one platform to another. • The configuration varies over time. For instance, the system is open to the introduction of new computational entities and likewise their deletion. The behaviour of the entities may vary over time. • The systems operate with incomplete information about the environment. For instance, information becomes rapidly out of date and mobility requires information about the environment to be discovered. The ultimate goal of the research action is to provide a solid scientific foundation for the design of such systems, and to lay the groundwork for achieving effective principles for building and analysing such systems. This workshop covers the aspects related to languages and programming environments as well as analysis of systems and resources involving 9 projects (AGILE , DART, DEGAS , MIKADO, MRG, MYTHS, PEPITO, PROFUNDIS, SECURE) out of the 13 founded under the initiative. After an year from the start of the projects, the goal of the workshop is to fix the state of the art on the topics covered by the two clusters related to programming environments and analysis of systems as well as to devise strategies and new ideas to profitably continue the research effort towards the overall objective of the initiative. We acknowledge the Dipartimento di Informatica and Tlc of the University of Trento, the Comune di Rovereto, the project DEGAS for partially funding the event and the Events and Meetings Office of the University of Trento for the valuable collaboration

    Innovation in symbolic industries: the geography and organisation of knowledge sourcing

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    This paper deals with geographical and organisational patterns of knowledge flows in the media industry of southern Sweden, an industry that is characterised by a strong ‘symbolic’ knowledge base. Aim is to address the question of the local versus the non-local as the prime arena for knowledge exchange, and to examine the organisational patterns of knowledge sourcing with specific attention paid to the nature of the knowledge sourced. Symbolic industries draw heavily on creative production and a cultural awareness that is strongly embedded in the local context; thus knowledge flows and networks are expected to be most of all locally configured, and firms to rely on informal knowledge sources rather than scientific knowledge or principles. Based on structured and semi-structured interviews with firm representatives, these assumptions are empirically assessed through social network analysis and descriptive statistics. Our findings show that firms rely above all on knowledge that is generated in project work through learning-by-doing and by interaction with other firms in localised networks. The analysis contributes to transcending the binary arguments on the role of geography for knowledge exchange which tend to dominate the innovation studies literature.knowledge base; cultural industry; regional innovation system; network analysis; Sweden

    Online Learning and Experimentation via Interactive Learning Resources

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    Recent trends in online learning like Massive Open Online Courses (MOOCs) and Open Educational Resources (OERs) are changing the landscape in the education sector by allowing learners to self-regulate their learning and providing them with an abundant amount of free learning materials. This paper presents FORGE, a new European initiative for online learning and experimentation via interactive learning resources. FORGE provides learners and educators with access to world- class facilities and high quality learning materials, thus enabling them to carry out experiments on e.g. new Internet protocols. In turn, this supports constructivist and self-regulated learning approaches, through the use of interactive learning resources, such as eBooks

    Fusing Loop and GPS Probe Measurements to Estimate Freeway Density

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    In an age of ever-increasing penetration of GPS-enabled mobile devices, the potential of real-time "probe" location information for estimating the state of transportation networks is receiving increasing attention. Much work has been done on using probe data to estimate the current speed of vehicle traffic (or equivalently, trip travel time). While travel times are useful to individual drivers, the state variable for a large class of traffic models and control algorithms is vehicle density. Our goal is to use probe data to supplement traditional, fixed-location loop detector data for density estimation. To this end, we derive a method based on Rao-Blackwellized particle filters, a sequential Monte Carlo scheme. We present a simulation where we obtain a 30\% reduction in density mean absolute percentage error from fusing loop and probe data, vs. using loop data alone. We also present results using real data from a 19-mile freeway section in Los Angeles, California, where we obtain a 31\% reduction. In addition, our method's estimate when using only the real-world probe data, and no loop data, outperformed the estimate produced when only loop data were used (an 18\% reduction). These results demonstrate that probe data can be used for traffic density estimation
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